Skoda Rally Blog

… starts on a Friday afternoon.  After the previous day’s debacle, I had arranged for the engine to be taken back and a full refund.  But this of course meant I needed to build the other one, and the parts had arrived.  The first task is to change the main bearings, which was done in short order as the whole engine was in bits.  Oiled up and with the crank in place it turned over easily, which seemed a good sign, so I then got on with the least favourite bit, getting the liners in; they are free in the Skoda block, and they need to be shimmed to the correct height above the deck and also relative to each other.  This is a slightly tedious process and it took an hour or so to get them in correctly.  Next would be fitting the pistons to the conrods, which should be straightforward, but I wanted to check the pistons were OK, and found… a problem.

The piston/liner set I’d been supplied with had been made up from a set of liners with different pistons as my engine is a 136 (high compression), and the set the supplier had got was a 135 (low compression) set.  And checking the pistons showed that they weren’t all the same size.  Normally, this would have been a case of the fat lady singing on the engine, but as luck would have it, I had a single spare one I’d bought years ago and stored, and it was the right size!  How convenient.  So with that luck out of the way, the rest of the engine was built up – conrods on pistons, rings on conrods, pistons into bores (carefully to avoid any issues like before), and then finally conrods onto the crank.  Within an hour or so, I had a working bottom end.  Camshaft was now fitted and it was time to check the timing – manufacturing tolerances can mean all sorts of issues with cam timing, and this is a crucial setting that determines the engine’s performance and character.  Mine needed to be with the inlet valve reaching maximum opening at 108 degrees, and I was finding it difficult to measure accurately with the head off, taking the measurement just from the cam, so i needed to fit the head and then take it from there.

Bottom end, ready for the head.

Unfortunately, an error occurred here which cost me a lot of time – I have a ‘degree wheel’ fitted to the crank, and I managed to disturb it by turning the engine the wrong way and loosening the nut that held it.  This happened after I’d fitted the head gasket, so I needed to measure it accurately again which meant I had to make up a special tool to allow this, and then re-set the wheel accurately.  Another two hours gone, but thankfully the cam was timed up perfectly.  Last time I needed to make up an offset key, and that took me a couple more hours to get right.

So, I finished building the engine, fitting the oil pump, sump and other covers, and got it bolted to the gearbox in time for lunch.  Splendid, I was back on course.

After lunch, I fitted the engine to the car (with mum’s help as ever), and the properly-jointed exhaust manifold made fitting much easier as I could take it off, fit the engine/box and then fit it afterwards, rather than try to get it on and then lift the engine into place.  Everything else went pretty smoothly, and 2 hours after stepping out the whole lot was back in the car and ready to run.

But would it run?

In short, YES!  It fired up near-instantly, and this was despite me accidentally leaving one of the injector plugs off so it ran on 3 cylinders briefly.  With that fixed, it fired up without hesitation, and I revved it up a few times and held it at various RPM as people suggest with a new engine.  All seemed OK aside from the paint on the new manifold burning off (it looked like the car was on fire at one point!).  A few more checks and changes and it was back on its wheels and ready to drive, but I called time as I was pretty tired.

Sunday saw me drive the car for the first time, and it moved without issue; I could instantly feel (and hear!) the diff working when I moved it, and with everything double-checked I went for a first drive.  Several things were noted; firstly the car ran pretty well considering it was mapped for the old camshaft, not the new works one that’s fitted now.  Secondly, there was still a lot of smoke (which turned out to be because the dipstick was the one thing I’d forgotten so it sprayed oil directly onto the exhaust – no big deal once I’d fixed it).  But thirdly, I had a problem.  There was no oil pressure at tickover once the car was hot.  This had been a problem before with a couple of other engines, and given the new bearings and so on I wasn’t expecting it.  However, I thought it may be that the oil was getting hot, so I fitted an oil cooler (which I handily had, I’d never fitted it), but alas this didn’t make too much difference (although it won’t hurt when in competition, I’m sure).

An oil cooler at last!

And from the side.

I have done some asking on the rally forum and the general consensus is that thicker oil (such as 10W60) will sort it, and also that I should take a look at some of the oil pump mechanism where the oil gets sucked in and the pressure relief valve.  I’m erring on the side of caution and have ordered a new oil pump body (the front cover of the engine makes this part up) and a new oil strainer/sucker to hopefully eradicate this permanently with all three.  If not then there’s clearly a problem with the crank bearing clearances, and if that’s the case then I will have to get a regrind done; I have a spare crank which can be ground down to the current size I am at with this engine, so I am not despairing (yet!), but it’s not ideal as it will mean engine out to get the crank out, so another weekend’s work in total to do that.  I really hope it doesn’t come to that…